Extend Multisite support

[aamplugin]

Extend multisite support by allowing admin to restrict access to non-members to any sub-site by just toggling the option on the AAM "Settings" tab. For more information refer to the documentation.

• https://aamportal.com/reference/advanced-access-manager/setting/non-member-access-restriction
• https://aamportal.com/reference/advanced-access-manager/setting/unified-multisite-configuration-sync